no peace in quiet
by Theoretician
Summary: The Shredder is dead, but Karai still can't sleep. (S4 canon divergence/fix-it fic, Donnie Karai bonding. Also posted on AO3)


For the third time in as many nights, Karai lay awake, looking at nothing in particular in the darkness. The same scene played over and over in her head—lashing out and hitting Shredder squarely in the chest, the bizarre sensation of his heart squishing as her fist made contact with it, the way he fell to the ground and just lay there. His heart didn't stop, but it didn't beat, either. It had simply quivered, and Karai had watched it for several minutes, waiting for something to happen, but nothing ever did. His heart twitched, and then it stopped, and he was dead.

There hadn't been any time to investigate his body. Once the Shredder no longer posed a threat, most of the focus had shifted to Leo, whose injuries were the most severe. No one asked Karai what had happened until many hours later, after Donatello and Splinter had stabilized Leo, and Donatello had calmed down from his second panic attack of the night. Even then, the mechanism of death wasn't very important to anyone. All that really mattered was that Shredder was dead, and the family was finally safe.

Still, Karai lay awake, thinking.

She turned onto her back, and caught the glow of a handheld video game coming from Donatello's bed. They were sharing his room for the time being—she wanted to be near her family while they healed, and his was the only room that had enough floor space for an extra futon. He was a quiet roommate, preoccupied with caring for Leo, and often lost in his own thoughts. They rarely talked. Of all the brothers, Karai found him to be the most enigmatic and reserved, at least towards her.

"Donatello?" she said out loud. She saw him sit up slightly, then lay back down.

"Sorry," he said, "is the light bothering you?"

"No. I can't sleep anyway."

A long moment crept by. Karai stared at the ceiling, and Donatello went on playing his game.

"Are you thinking about Shredder?" he asked at length.

"Yeah."

Another long pause.

"Do you feel guilty?"

"No," Karai said immediately, "he deserved to die. I just don't understand how I did it."

"It might not have been you at all," said Donatello. "His mutation was seriously unstable. Maybe he was going to drop dead anyway."

Karai had thought about that. The mutation had practically turned Shredder inside-out, and inflated him to absurd proportions. It wouldn't be very surprising if his body really had just given up, but Karai kind of hoped that she _had_ been the cause of death. It would be so much more satisfying that way.

"Maybe," was all she said.

"You said his heart stopped?"

"Well, it kind of twitched for a while first, but yeah. I punched it, and it stopped."

"What do you mean, 'it twitched'?"

Karai shrugged, even if Donatello couldn't see her. "It just… twitched. Like it was trying to beat, but couldn't do it. I don't know how else to describe it."

Donatello was quiet. The light on his DS turned off.

"Do you want to find out what happened?" he asked. Karai sat up.

"Are you offering to help me?"

"Yeah. I guess I am."

"Then, hell yeah, I want to find out."

The lamp over Donatello's bed went on, and he tossed his blanket back.

"Come on," he said as he stood, "I want to check on Leo, anyway."

Karai gladly got to her feet, and they went through the lair to the laboratory, taking care to step quietly past Mikey and Raphael's bedrooms and the dojo. Donatello lit the way with his T-phone, since the only light came from streetlights filtering through the grates, high above in the ceiling. Without checking a clock, Karai guessed that it was two or three in the morning.

In the lab, she sat down at the computer and booted it up while Donatello went over to where Leo lay, hooked up to homemade vitals monitors. His brother had been badly injured in the fight—a broken shell, shattered kneecap, fractured ribs and a concussion besides all the scrapes and bruises that came with any fight, but Donatello had done surprisingly well with what he had, and Leo would recover in time. As Karai watched Donatello check the vitals readings and make a few careful adjustments, pride twinged in her chest. She didn't say anything, though. Her opinion didn't hold much weight for him, she suspected, not yet.

The only other chair in the lab was buried under Leo's gear that no one had bothered to put away yet, so Karai swapped places with Donatello and stood behind him, watching the computer screen as he opened the web browser.

"I still can't believe you guys have an internet connection down here," Karai said. "Sometimes I have trouble connecting when I'm sitting in the _middle_ of an internet café downtown."

"I made some modifications to our hook-up," Donatello replied offhandedly. He typed _heart stops after impact_ into the search bar. "It's not exactly legal. Commotio cordis," he added, reading off of the top result. "That was easier than I thought it would be. This says if you hit the heart at the right time in the cardiac cycle, you can trigger ventricular fibrillation, and it'll stop after a while."

Karai squinted at the screen, skimming the first paragraph of the article. Then, she shook her head. "I wouldn't know if that's it. I don't know what ventricular fibrillation is."

"It's when the heart just quivers, instead of pumping properly."

"That sounds right."

"If that's the case," said Donatello, "then you were really, _really_ lucky. The chances of hitting his heart at the right time are…" He shook his head. "They're tiny. Plus you have to hit it at the right angle, with enough force—although, I don't think you would have any trouble with _that_ part."

"That sounds like a compliment," Karai said, smiling. Donatello looked over his shoulder at her, and she struck a pose, flexing her arms. That made him grin, and Karai's chest felt warm. "So, commotio cordis?"

"I guess if you wanted to name an official cause of death, that would be it." Donatello swiveled his chair around to look fully at Karai. "It's a little…" He trailed off, and Karai nodded.

"Anticlimactic, I know. After all this, a heart attack? That's all it took?" She moved around Donatello to sit on the table, beside the computer. "It would have been so much more satisfying to stab him or something." She made a sharp gesture as she spoke, mimicking the slashing of a blade.

"You don't feel bad about it at all?" Donatello asked, a bit shyly, and Karai shook her head.

"I know what you're thinking," she said, "but he wasn't my father. He played at loving me, but I was just a bad consolation prize to him. He wanted my mother."

Donatello looked at the floor, away from Karai. She had expected this to some degree.

"It doesn't hurt," she said. "Not anymore." She turned her hands palm-up and shrugged. "I don't know. It's hard to explain unless you know what it's like, and I hope that you never do."

"I'm sorry," Donatello said quietly.

Karai shook her head again. "I don't want sympathy. I want to fix things. Make my own legacy, instead of living in the shadow of that piece of trash who raised me."

She looked over to where Leo lay, sleeping peacefully.

"I'll keep on destroying Shredder's empire," she said. "I'll rebuild it from the ground up if I have to, and make it my own."

Donatello followed her gaze towards Leo, and they sat quietly for a minute, though not as tensely this time.

"I'll do it right this time," Karai said, her voice softer than before. "I won't try to drag you guys into it. I don't want you to get hurt again."

"Listen," Donatello said, and Karai looked at him. He was still watching Leo, but he spoke to her. "You don't… have to do things by yourself anymore. We'll have your back."

Karai smiled. She could believe it this time. "Thank you, Donatello."

He looked at her now, and returned her smile. "That's what brothers are for."


End file.
